I am trying to find the address and phone number of a youth soccer
academy based in Los Angeles.It is a mexican club, called 'Chivas' or
'las chivas'Thankyou.

The name of the club you are looking for is "Club Deportivo Chivas
USA". From the information found on sportsencyclopedia.com,

"Owner Jorge Vergara is the owner of Mexico's storied soccer club,
Chivas de Guadalajara. On September 22, 2004, Vergara and club
officials unveiled the seemingly obvious choice of "Chivas USA" and
the club is supposedly meant to reach out to Los Anegeles' large
Mexican community."

Their first season game is on April 2nd, and you can find lots of more
information on their website, including rosters, etc. They play out of
the Home Depot Statdium, and their contact information follow below.

18400 Avalon Blvd.
Suite 500
Carson, CA 90746
Phone: (310) 630-3606
1-877-CHIVAS-1

Relavant links:

http://www.sportsecyclopedia.com/mls/cd/chivasusa.html
http://chivas.usa.mlsnet.com/MLS/cdc/

a thorough answer... I assume that the youth league is also based
there too...thanks!